Gliederung

QT dispersion (QTd) reflects repolarization heterogeneity caused by a divergence of the repolarization duration of the adjacent myocardial areas. Patients with previous myocardial (MI) infarction reveal increased QT dispersion putting them at higher risk of life-threatening arrhythmias and sudden cardiac death. Shortening of QT interval during exercise results from heart rate acceleration and beta-adrenergic stimulation. A goal was to assess an effect of rehabilitation performed in 65 patients with previous MI treated with PTCA on QT dispersion.

Material and method: A study population was divided to the two groups: A – 33 patients (mean age: 58,6Â±1,8 years) who underwent 6-month rehabilitation, and B – 32 patients (mean age: 61,4Â±1,5 years) not subjected to rehabilitation. A and B groups showed the comparable echocardiographic parameters: EF(%) – A, 55.0Â±1.8; B, 53.6Â±1.2; and LVEDD(mm) – A, 54.3Â±0.1; B, 54.5Â±0.1. The mean time from PTCA and the follow-up onset was similar for A and B groups: 6.7Â±1.2 vs 6.1Â±0.8 months. On the 24-h Holter monitoring, the both groups revealed ventricular arrhythmia max.III Lown’s class. Rehabilitation comprised 45-min cycloergometer training repeated 3x/ week and general improving exercises – 2x/ week. Cycloergometer loads, given at 4-min intervals, were interrupted by 2-min rest with low load.

Results: QT dispersion values were measured before and after the 6-month rehabilitation, based on the standard 12-lead ECGs recorded at rest prior to the treadmill test. The mean value of QTd assessed in the group A decreased significantly from 65.1Â±4.7 ms to 54.0Â±3.8 ms (p<0,01). In contrast, in the group B, without rehabilitation, only slight reduction of QTd was observed after the 6-month period: 69,9Â±2.8 ms vs 69,4Â±2,7 ms (NS).

Conclusion: Cardiac rehabilitation had a beneficial effect on QT dispersion in the patients with previous MI and PTCA, diminishing a risk of arrhythmias.